1. Field of the Invention
The present invention relates generally to semiconductors and, more particularly, to power metal-oxide-semiconductor transistors and methods of fabricating and using same.
2. Description of Related Art
A lateral power metal-oxide-semiconductor field effect transistor (MOSFET) is a MOSFET fabricated with coplanar drain and source regions. Such transistors are known to support applications such as the control of electric motors. In typical applications, a power MOSFET may function as a switch controlled by gate-to-source voltage which effectively opens or closes (i.e., respectively, turns OFF or ON) a connection between the power MOSFET's drain and source.
When in an ON state, the power MOSFET should exhibit a specific on-resistance as small as possible in order to minimize power losses in the device. The on-resistance is proportional to the rate at which heat is generated by current in the device. The larger the on-resistance of the device, the less efficient the device. Accordingly, it is desired to reduce this resistance as much as possible.
The device should also have a capability to support high voltages (e.g., in excess of 700 V) without breakdown when in the OFF state. Breakdown voltage of the lateral power MOSFET should be maintained in spite of high voltage (e.g., 80% of maximum voltage or at least 560 V when maximum voltage is 700 V) applied to the drain side of the device for a long time. A conventional lateral power MOSFET exhibits a specific on-resistance of about 115 Ω-mm2.
A need thus exists in the prior art for a lateral power MOSFET having a specific on-resistance less than 100 Ω-mm2 while maintaining a breakdown voltage greater than 700 V.